The embodiments described herein relate generally to nacelle assemblies for wind turbines and, more particularly, to a yaw bearing within a nacelle assembly.
At least some known wind turbines include a yaw bearing between a nacelle and a tower of the wind turbine. The yaw bearing allows the nacelle to be rotated with respect to a direction of the wind. More specifically, the yaw bearing usually includes gearing and a yaw drive motor rotates by the nacelle by engaging the gearing of the yaw bearing.
At least some known yaw bearings are slew bearings that include concentric races. Between the concentric races, the slew bearing can include balls, vertically oriented rollers, and/or a slide surface. The gearing can either be located on an inner surface of an inner race or an outer surface of an outer race. Either the inner race is coupled to the nacelle and the outer race is coupled to the tower, or the inner race is coupled to the tower and the outer race is coupled to the nacelle. The race coupled to the tower includes the gearing. To control the yaw of the nacelle, the yaw drive motors rotate against the gearing to pivot the nacelle about the tower. Yaw brakes are used to prevent the nacelle from rotating when the yaw drive motor is not operating. Also, during yawing, the yaw motors drive against yaw brake calipers, which are partly released and/or engaged, such that the yawing motion is smooth. Further, such slew bearings require high precision fabrication and/or manufacturing, which may be time-consuming and/or costly.
At least some other known yaw bearings are slide bearing that do not include balls and/or roller between races of the bearing. Such slide bearings includes slide surfaces having a lubricant therebetween. However, such lubricant may deteriorate and/or slide surfaces may wear during use of wind turbine. Accordingly, there is a need for a yaw bearing that does not require yaw breaks and/or high precision manufacturing and/or fabrication. Further, there is a need for a yaw bearing that does not include lubricant and/or surfaces that wear during use of the wind turbine.